Back-of-the-envelope count of Facebook's audience in India

Estimate how many people in India use Facebook. Explain how you set up the estimate, state each assumption, and arrive at a figure with a range. ```hint Narrow the population in stages Go from everyone in India to the people who could plausibly use the product, then to those who actually do, and decide which groups need their own rates at each stage. ``` ### Clarifying Questions - Should the figure be registered accounts, monthly active users or daily active users? - Are we counting people or accounts, given that some people keep several accounts and some phones are shared by a whole family? - Is this a figure for today, or should it project growth as more of the country comes online? ### What a Strong Answer Covers - A defined user metric and unit (people or accounts), settled before any arithmetic - A top-line equation that narrows from India's population to people who can reach the product and then to people who use it - Segmentation along the dimensions that most change internet access and adoption in India, with labeled round assumptions and a rationale for each - Arithmetic that is correct and easy to follow - A sanity check from a second angle, a final range, and how the figure translates across user definitions ### Follow-up Questions - How would you convert your figure to daily active users, and what ratio would you assume? - Which assumption would you validate first, and with what data? - How would you project the number five years out, as cheaper phones and data bring more rural users online?